There are X-ray fluoroscopic apparatus for enabling, in addition to diagnosis of the alimentary canal including the stomach, also X-ray radiography of the chest. However, it is necessary to secure a longer distance from an X-ray source to an imaging device (hereinafter called FFD: Focus Film Distance as appropriate) at a time of chest radiography than at a time of alimentary canal diagnosis. For example, it is about 1.8 to 2.0 m in the case of chest radiography, as opposed to 1.1 m in the case of alimentary canal diagnosis. FIG. 10 shows a conventional X-ray fluoroscopic apparatus constructed to be capable of such multipurpose fluoroscopy. FIG. 10 shows front views of the conventional X-ray fluoroscopic apparatus, in which (a) shows a state of a top board being horizontal, (b) shows a state of the top board being inclined, and (c) shows a state of the top board being vertical. As shown, the conventional apparatus includes a tiltable top board 61 for supporting a patient M, an X-ray tube 63 disposed above the top board 61, a cassette 65 disposed below the top board 61 to be opposed to the X-ray tube 63 and loaded with a film, a strut 67 for supporting the cassette 65, and a support arm 69 extendible and retractable relative to the strut 67 for holding the X-ray tube 63. The top board 61 is held by a top board support (main frame) 71, and the main frame 71 is supported by a pedestal 77 to be rockable through a pinion 73 and sector rack 75. The top board 61 tilts up and down by rotating with the main frame 71. The strut 67 is supported through a drive mechanism, not shown, mounted in the main frame 71, to be movable longitudinally of the top board 61 by the drive mechanism and rotatable with the main frame 71. The X-ray tube 63 has a collimator 81 attached thereto. In an alimentary canal diagnosis using the conventional X-ray fluoroscopic apparatus constructed in this way, fluoroscopy is carried out with the support arm 69 retracted to shorten the focus film distance. At this time, as shown in FIGS. 10 (a) and (b), the top board 61 is usually tilted with a patient M placed thereon. In a chest radiography, radiograms are taken with the support arm 69 extended to lengthen the focus film distance. At this time, as shown in FIG. 10 (c), the patient M usually takes a standing position (see Patent Document 1, for example).
[Patent Document 1]
Unexamined Patent Publication No. 2005-287668